Defects of integrin recycling in Sac2 null cells. (A) Flow cytometry analysis of surface integrin in WT (black) and ΔSac2 (red) cells. (B) Quantitative analysis of the mean intensity shown in A. Data are from three replicate experiments (n = 10,000; mean ± SEM). (C) Western blot probed with anti–β1 integrin, anti-tubulin, and anti-Sac2 of cell lysates prepared from WT and Sac2 null cells. (D) Intracellular distribution of β1 integrin in WT and ΔSac2 cells. The mean fluorescence intensity in nonpermeabilized and permeabilized cells and the SEM are shown in the right panels (n = 5). (E) Recycling assay of β1 integrin. Bars, 10 µm. The mean recycled fluorescence intensity in nonpermeabilized and permeabilized cells and the SEM are shown in the right panels (n = 5). **, P < 0.01.